Piston-valve and steam-passage in cylindrical steam-chests



UNITED STATES PATENT OFFICE.

JOSEPH MARKS, OF BOSTON, MASSACHUSETTS.

PISTON-VALVE AND STEAM-PASSAGE IN CYLINDRICAL STEAM-CHESTS.

Specification of Letters Patent No. 10,454, dated January 24, 1854.

To all whom, it may concern:

Be it known that I, JOSEPH MARKS, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Valves for Steam-Engines, and that the following description, taken in connection with the accompanying drawings hereinafter referred to, forms a full and exact specification of the same, wherein I have set forth the nature and principles of my said improvements by which my invention may be distinguished from others of a similar class, to-

gether wit-h such parts as I claim and desire to have secured to me by Letters Patent.

The figures of the accompanying plate of drawings represent my improvements.

Figure 1, is a central longitudinal vertical section of an engine cylinder, with my improved arrangement of valves attached. Fig. 2, is a transverse vertical section of the same taken in the plane of the line A, B, Figs. 1 and 3. Fig. 3 is a horizontal section of the steam chest and cut off valve chest, taken in the plane of the line C, D, Fig. 2. Fig. 4 is a plan or top view of the interior of the cut ofi valve, or piston on an enlarged scale. Fig. 5 is a central longitudinal vertical section of the main valve or piston also enlarged. v

The disadvantages attending the use of the valves ordinarily employed in steam engines, are well known and arise principally from the unequal pressure of the steam upon different portions of the valve, thereby causing considerable friction and wear between the valve and its seat, with the consequent and proportional expenditure of power to work the same, and the necessity of frequent repairs.

My improvements are designed to obviate these objections, by so arranging and constructing the valves and their seatsor steam inder at the first movement or opening of chamber 71 i of the steamchest, '0, c.

aperture, 0, Fig.2. When steam is the valve, and an equal rapidity in exhausting the steam from the same, which result is obtained by, and forms one of the principal advantages of my improvements, as by the shortest movement of the valve a very Elarge area of passage of the steam.

0: a in the drawings represents the cylinder of a steam engine and b the piston.

c ccZ cl are two'cylindrical steam chests port is opened for the communicating with each other, and having p circularports or passages, the arrangement of which will be hereinafter explained." In

each of these steam chests is placed a'piston valve .of-peculiar construction actuated in the usual manner by eccentrics.- In the-'- steam chest at d, e e, is the inducting-passage through which steam is 'admittedfromthe boilers into a horizontal chamber, f, which communicates at both its ends with-two circular passagesg g'g 9, formed in and extending wholly around the interior of the steam chest cl (Z at each end of-the same- .The remaining central passage h, h, of this steam chest 0? ol is circular, and communicates directly with the long passage: or-v chamber, 75, 2' opens at both ends intothe circular ports 70 lc'7a 7c at each endof the The A steam chest, 0, c, which has in all five circular ports or passages extending completely around the interior of the cylinder, the two i circular ports Z ZZ Z communicating with the chambers m, m,.which lead respectively,

to each end ofthe cylinder at a. The central port'n, ca, in the steam chest 0 0, ex-; tends, like all the others, completely around the interior of the same, and is the one through which theexhaust steamfrom the cylinder passes andescapes through the ducting circular ports 9 g, g g at the ends firstradmitted from the boiler into the chamber 7, it passes from the same simultaneously into both the inof the steam chest, thuscausing an equal pressure upon both ends of the cylindrical piston valve or cut ofi',,;0, shown inclevation by red lines in'Fig. 3. The movement of the valve, 0,then begins to open the center port bit, into which the steamenters and passes to the chamber, 71 i of'the steam chest, 0, 0. 'After the'port, h it, has

been entirely opened to admit suflicient steam, the valve, 0, begins toreturn and closes the port, h,- so'as to prevent. any

more steam from entering the steam chest 0 c, (and consequently to the cylinder a a) and permitting the steam already received to act expansively. It will readily be seen that when the steam enters the center port, h it, that it passes entirely around the periphery of the valve, thereby insuring, as the steam at the same time presses upon both ends of the valve, an equal pressure upon all portions of the same, and keeping it in equilibrium so that it can be moved easily and with very little friction in either direction.

The piston valve of the steam chest 0, 0, or main valve is composed of two heads, 2), 79, fitting closely in the steam chest and united by a cylindrical portion, (9,) of less diameter as shown in elevation by red lines in Figs. 1 and 3 and in section in Fig. 5. When the steam enters into the chamber 71 i of the steam chest 0, c, it passes at the same instant to both ends of the valve, 20, p, g, and fills the space between the heads of the valve and the end of the steam chest. \Vhen by the traverse of the valve one of its heads has passed either of the ports, Z Z, so as to open the same, the steam, following the valve, enters this port, passes through one of the chambers, m, m, of the cylinder, a, a, and forces up the piston, b, of the'same. As soon as the piston, Z), has been forced up, the opposite cylinder port, Z Z beginsto open by the return of the valve, 7?, 9, so as to admit steam into the other end of the cylinder,

a, a, and thus force the piston I) back and expel from the cylinder the steam first ad mitted. At this time the cylinder port, Z Z, through which steam first passed to'the cyl- 'inder has been closed so as to prevent any more steam from entering thesame by the return of the valve p, g, the head of which 'passes beyond the port Z Z toward the end of the steam chest, thereby, as the valve is cut out or of less'diameter at between the heads; opening a full communication between the cylinder port Z Z, and the exhaust port, 12,, n. Thus on the return of the piston 'r the steam will escape through the port Z Z into the circular exhaust port or passage, n, n, as shown by the arrows in Figs. 1 and 2. This operation of receiving, cutting OE, and exhausting steam is repeated in the usual manner of working steam expansively.

From the above description it will be seen that the piston valves 0, and p, g, are at all times subject to an equal pressure of steam in every direction, both on their ends and around their surface, and that by thepeculiar shape of the main valve, 79 g, this equality of pressure is also kept up during the time the steam is being exhausted from the cylinder a, a, as the portion of the valve, 9, between its heads p p, is completely surrounded by the exhaust steam. The advantage of this equilibrium of pressure upon ment in the piston valves and piston of the steam cylinders, which consists in an arrangement by which the metallic packing rings of the same are made more flexible and elastic than those heretofore used, whereby they will more readily adapt themselves to any inequalities in the bore of the steam chests'and travel more smoothly in the same and insure a closer and more perfect fit. This improvement is represented in Figs. 4 and 5, and consists in using, to press against and set out the expansion rings, 8, 8, usually employed for the metallic packing rings of a piston, one continuous bent spring a, 'u with set screws '0, w, '2), for adjusting the same. Each of these screws bears at one end against a washer w, which presses upon the packing rings, .9, s, and has a nut, w, by which thespring, u, u, can be forced toward or away from the rings, 8, s, at pleasure. The rings, 8, s, are surrounded by two expansion rings 25, t, in the usual manner. The spring, a, u, passes around the core block a (triangular) ofthe piston, and where the set screws pass through it is bent in toward the center of the piston. By this arrangement any pressure upon one portion of the piston head is immediately diffused by the spring to all parts of the packing rings, thus forming a piston head which is extremely flexible and yielding, and which will adapt itself closely to the steam chest or cylinder in which it is moving, so as to insure a perfect fit. Inconstructing a piston head in the usual manner, with short separate springs adjusted by set screws, it will be seen that the packing rings can only yield or be adjusted at the parts in cont-act with the said springs, whereas by my improvements the spring u, u, bears at all times equally upon all parts of the rings, and when the bent portion of the spring, between the bearing points of the core block a, is'pressed in by the rings 3, 8, this pressure is diffused throughout the whole spring so as to throw out the rings, 8, s, and cause the outer expansion rings t t to fit tightly against the inner surface of the steam chest and cylinder. 4

In order that the main valve, 9, and cut off, 0, may not abut against the edges of the, steam ports in their travel forward andback four narrow guides orbearlngs y, y, &c.,

are formed in the steam chests,level and forming one surface with the partitions between the ports.

In the foregoing description my improvements are represented as applied to steam engines; but it will be evident that they are equally applicable also to air and gas engines, &c.

I claim I 1. Constructing a steam chest with continuous circular ports or passages, both for the induction and exhaust steam, arranged as herein above described, so as to keep a constant and equal pressure of steam upon both ends and the periphery or outer surface of a cylindrical piston-valve, which travels in the bore of the same, and by which also is secured a large area of port by a very small movement of the valve, and: this I claim whether the said valve be used as a main valve, cut oii' or throttle valve.

2. I claim the combination of a piston valve composed of two heads, which fit closely in the bore of the circular steam exhaust chamber 1% n. 1 l

' JOSEPH MARKS. f

Witnesses:

JOSEPH GAVETT, F. R. LINCOLN. 

